Electric lamp



(No Model.)

B. M. POX.

ELECTRIC LAMP.

No. 250,227. Patented Nov. 29,1881.

(i f y y WITNE INVENTOR:

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' BY ATTORNEYS.

' UNITED STATES PATENT OFFICE.

EDWIN M. FOX, OF NEW YORK, N. Y.

ELECTRIC LAMP.

SPECIFICATION forming part of Letters Patent No. 250,227, dated November 29, 1881,

Application filed May 21, 1881. (No model.)

To all whom it may concern:

Be it known that I, EDWIN M. Fox, of the city, county, and State of New York, have invented a new and useful Improvement in Electric Lamps, of which the following is a specification.

My improvements relate to electric lamps of that kind which give light by the incandescence of a piece of carbon contained in the vacuum-chamber.

The improvements consist in the form of theglass chamber, in combination with theconducting-wires, the holders for the carbon, and a reflector; and also, further, in the peculiar form of carbon, as will be hereinafter fully described.

In the accompanying drawings, Figure l is an elevation, partly sectional, of a lamp of my invention. Fig. 2 shows the carbon loop sepa rately; and Fig. 3 is a detail of the means for holding the carbon.

Similar letters of reference indicate corresponding parts.

A is the vacuum'chamber, formed of glass. The shape of the chamber is approximately oblate spheroidal, with nipples a a at the ends, through which the wires b b pass. At 0, on the under side, is formed the tube through which the chamber is to be exhausted.

(I is the carbon loop, held by clamps c on the ends of wires b.

At its rounded upper side the chamber is provided with a reflectingsurface, which is formed by suitable material applied directly to the glass, or which may be in the nature of a separate reflector. The obj ect of this reflector is to concentrate the rays of light and throw downward the rays that would otherwise be practically lost when thelamp is used for streetillumination and in elevated positions.

The loop d, of carbon orcarbonized material, is an oval or flattened ring, and thus forms a double connection between the two wires, which has the effectto split thccurrent, so that there will be two lines of incandescence, slightly separated. The light will, for this reason, be less intense and more soft than when a single ribbon of material is used. This shape also gives a wide surface at the ends for the clamps to take upon, so that the carbon is held firmly and securely.

The clamps c consist of two flat strips of metal, the longer strip being connected to the wire, and the shorter spring-strip riveted or otherwise connected thereto. The ends are fitted with a slide, d, by which they are pressed together.

With regard to the form of the carbon I would state that I do not claim, broadly, a ring-shaped carbon, as this is not new. This feature of my invention is distinctive in being a simple elongated loop with its prolate ends wider than its oblate sides. The oblate sides,

in approaching each other closer than the opposite sides of a circle, give a practically solid light with no opening in the center, and yet this light is sufficiently softened and diffused by the double conductors as to avoid the objectionable concentrated intensity of a single conductor. The widened prolate ends are also distinguishing features which serve to give a better bearing for the carbon-supports.

In relation to the peculiar form of the vacuum-chamber, it will be seen that when its oblate spheroidal form is drawn out to constitute the nipples a for the conducting-wires the longitudinal outlineof the lamp becomes parabolical, or the form most favorable for the best reflection, while the nipples give passage to the conducting-wires without special collars or other appliances.

Having thus described myinvention, Iclaim as new and desire to secure by Letters Patent- 1. In an electric lamp, the oblate spheroidal vacuum-chamber drawn out into parabolic outline to form nipples to for the conducting-wires, in combination with said conducting-wires entering the lamp through said nipples, a reflector of corresponding shape placed upon the flat side of the chamber, and a carbon supported upon the conducting-wire, substantially as and for the purpose described.

2. The carbon d, made in the form of a flat elongated loop, with its prolate ends wider than its oblate sides, as and for the purpose described.

EDWIN M. FOX.

Witnesses:

GEo. D. WALKER, O. SEDGWIOK. 

